This invention relates generally to a hydraulically operated tool and to a valve for controlling operation of the tool.
The tool with which the invention is concerned comprises a tool member which is shifted through active and return strokes by a reciprocating hydraulic actuator. The actuator may be of the double-acting type which shifts the tool member in one direction when pressurized oil is supplied to one side of the actuator and returns the tool member in the opposite direction when pressurized oil is supplied to the other side of the actuator. In other tools, the actuator may be of the single-acting type in which the tool member is shifted in one direction when pressurized oil is supplied to one side of the actuator and then is returned by a spring when the hydraulic pressure on the one side of the actuator is relieved by exhausting the oil from the actuator.
The control valve with which the invention is concerned is a four-way valve and may be of the same general type as disclosed in Hutson U.S. application Ser. No. 628,152, filed July 5, 1984 and entitled Three-Position, Four-Way, Short-Stroke Rotary Valve. In general, such a valve includes a valve member which may be shifted in opposite directions from a neutral position to first or second active positions. In the first active position of the valve member, pressurized oil is supplied through a first passageway of the valve and low pressure oil may be exhausted to drain through a second passageway. When the valve member is shifted to its second active position, pressurized oil may be supplied to the second passageway while low pressure oil may be exhausted to drain through the first passageway. Four-way valves conventionally are used to control tools having double-acting hydraulic actuators.
With most commercially available hydraulically actuated tools, the control valve is either connected to the hydraulic actuator by flexible hoses or forms a permanent part of the tool itself. In some cases, the presence of the hoses makes it difficult to manipulate and maneuver the tool. If the control valve is part of the tool itself, a separate control valve is required for each separate tool.